The present invention relates generally to a harrow of the type which is attached behind a cultivating device to break up the clods of earth turned up by the working parts of the device into smaller chunks so as to help level the seedbed being worked and to conserve soil moisture. One such harrow particularly designed for use in conjunction with a plow is constructed with a single mounting bar which extends across at least a portion of the path of the soil being worked by the plow. Attached to the bar is a plurality of soil-working teeth extending in a generally perpendicular direction from the bar for engagement with the soil to break up the clods. To adjust the action of the harrow for different soil conditions, the bar is secured pivotally with respect to the frame of the plow with an adjustable spring tension arrangement acting between the bar and the frame. With this arrangement, the teeth may be slanted at different rearward angles with respect to the soil in the direction which the harrow is being pulled through the soil. In addition, vertical adjustment of the mounting bar provides for setting the depth to which the teeth may embed in the soil at a given rearward angle so as to obtain the best working action from the teeth for a given set of soil conditions.
Examples of harrows of the foregoing type are disclosed in U.S. Pat. No. 3,100,018 and in a brochure entitled Pressure-Matic and Clod Buster Plow Harrows published by Royal Industries Noble Division of Sac City, Iowa.
While the single-bar harrow of the foregoing type has the advantage of being easily maneuverable with a plow, the harrow is found to be unacceptable for use with post-plowing cultivating implements such as a field cultivator or a disk harrow inasmuch as the chunks of earth left behind the harrow are not broken up sufficiently to provide a good seedbed for planting or for proper cultivation of a planted crop. To adequately break up and pulverize the chunks of earth into loose level soil behind the implement, present usage is to employ a large multiple bar field drag in conjunction with the implement. A multiple bar field drag is one including several spaced, parallel mounting bars connected together and extending laterally across the path of travel of the implement with each of the bars having a plurality of the soil-working teeth attached thereto and extending downwardly therefrom to embed in the earth. Although a multiple bar drag usually will do an adequate job of working the seedbed, due to the size of the drag it substantially decreases the maneuverability and handling of the implement to which it is attached both in the field and on the road. Moreover, owing to the weight added by the drag behind the implement, the drag may detrimentally affect the soil-working action of the implement itself. One example of a multiple bar field drag is disclosed in U.S. Pat. No. 3,043,377.